The 60-year-old reality star reflected on her relationship with Nicole and the O.J. Simpson murder trial in an interview for the Feb. 8 issue of People magazine. O.J. was accused of killing Nicole, his ex-wife, in 1994, but was acquitted of the crime the next year.
"[O.J. and Nicole] were two of the best friends I ever had in my entire life," Jenner said. "They were my family. O.J. was like my big brother. So I not only mourned the loss of Nicole, but I mourned the loss of O.J. and that relationship."
Jenner met the Simpsons through her then-husband, Robert Kardashian, who later served as O.J.'s defense attorney. Although the families were close for nearly 20 years, the reality star didn't learn O.J. and Nicole's marriage was abusive until the trial.
"She was funny, she was beautiful and loyal and passionate and the best mom I had ever met," she said of Nicole. "My heart breaks because of all the pain and suffering she went through. I wish I had noticed the signs. She was fighting for her life many days I'm sure. I try to pay attention to things more now."
Nicole helped Jenner through difficult periods despite her own troubles, including the star's miscarriage prior to daughter Kendall Jenner's birth. Jenner remembers Nicole as an "amazing friend," saying, "There were some really great precious moments we shared."
The O.J. Simpson murder trial will be dramatized on the FX series American Crime Story: The People vs. O.J. Simpson. American Horror Story creators Ryan Murphy and Brad Falchuk will executive produce the series, which premieres Feb. 2 at 10 p.m ET.
Selma Blair will play Jenner, with David Schwimmer as Kardashian, Cuba Gooding, Jr., as O.J. Simpson, Sarah Paulson as lead prosecutor Marcia Clark and John Travolta, Courtney B. Vance and Nathan Lane as defense attorneys Robert Shapiro, Johnnie Cochran and F. Lee Bailey.